OsDPR

Function:To investigate the biological function of OsDPR, we constructed the stable plant expression vector pCAMBIA1302-OsDPR::GFP and produced transgenic tobacco plants. Wild-type and T3 transgenic tobacco progeny were grown under identical conditions and observed simultaneously.Phenotypic analysis indicated that the shoots of OsDPR-transgenic tobacco plants were smaller than those of wild-type plants.The quantitative difference of seedling height between transgenic and wild-type plants is shown in Figure 5C. The roots of the transgenic tobacco plants were shorter than those of the wild-type plants under both iron-deficient and -sufficient conditions.The quantitative comparison of root length between transgenic and wild-type plants is shown in Figure 5D. OsDPR expression resulted in reduced sizes of aerial parts and roots,indicating that OsDPR impedes the growth of tobacco plants.The growth suppression caused by OsDPR was even stronger under iron-deficient conditions, because the roots of OsDPR-transgenic plants were even shorter than those of wild-type under iron deficiency.The phenotype of the OsDPR-transgenic tobacco plants indicated that OsDPR restrained overall plant growth, including growth of roots and shoots.OsDPR has a transmembrane domain near its C-terminus, but we did not detect membrane localization of OsDPR. It is possible that it is not a membrane protein, and that the transmembrane domain may be a hydrophobic part within the folding protein.There is a CpG island within the promoter and the adjacent exon 1 of OsDPR. Methylation of the CpG island might be involved in regulating the activity of the gene. We searched public databases with OsDPR, but found no proteins with high levels of amino acid sequence similarity.Therefore, OsDPR is a novel gene that participates in regulating plant growth.OsDPR is a rice gene induced by iron deficiency. Our results showed that it suppresses growth in both tobacco and rice plants. This suppressive effect may be a kind of adaptive response in plants under iron-deficient conditions. After years of evolution, plants have gradually acquired a variety of strategies to adapt to adverse environmental conditions.Under iron deficiency, some iron-related genes in plants,like IRT1 and FRO1, are highly expressed to enhance the efficiency of iron uptake. There are also some changes in morphology, such as more abundant and longer root hairs,which expand the area for iron absorption. While actively improving the plant’s ability to take up iron, plants might reduce iron use to keep growing with minimum nutrition consumption. The gene OsDPR is predicted to function in such an “economical” strategy. That is, when iron is insufficient,OsDPR slows the growth rate of plants, reducing the consumption of nutrients. This would enable the plant to survive with a low cost. Therefore, it is predicted that OsDPR plays a protective role in rice under iron deficiency.